Method of testing shortening

ABSTRACT

A method of qualitatively testing the free fatty acid concentration of shortening, including the steps of admixing a measured volume of the shortening in a container of an alcoholsodium hydroxide solution, including an alkaline indicator, and having a fixed alkaline concentration equivalent to a known concentration of free fatty acids; agitating the mixture; and observing any color change in the test solution.

United States Patent [72] lnventor Nathaniel P. Apter McKeesport, Pa.

[2]] Appl. No. 786,912

[22] Filed Dec. 26, 1968 [45] Patented Oct. 26, 1971 [73] Assignee Apter Industries, Inc.

[54] METHOD OF TESTING SHORTENING 1 Claim, 1 Drawing Fig.

[52] US. Cl 23/230 R, 252/408 [51] Int. Cl ..G0ln 31/22 [50] Field of Search 23/230, 231; 252/408 [56] References Cited OTHER REFERENCES Official and Tentative Methods of the American Oil Chemists Society, AOCS Official Method L3a- 57, May l6,

1959.TP671A5,1946.

Mehlenbacker, V. C The Analysis of Fats and Oils, The Garrard Press, Champaign, lll. TP67lM4. pages 98 and 99 relied on.

Primary Examiner-Morris O. Wolk Assistant ExaminerR. M. Reese Attorney-Buell, Blenko & Ziesenheim ABSTRACT: A method of qualitatively testing the free fatty acid concentration of shortening, including the steps of admixing a measured volume of the shortening in a container of an alcohol-sodium hydroxide solution, including an alkaline indicator, and having a fixed alkaline concentration equivalent to a known concentration of free fatty acids; agitating the mixture; and observing any color change in the test solution.

Pmmenm 26197! 3,615,226

mvzmon Nathaniel P. Apter METHOD or 'ms'rmc snoa'ranmc This invention relates to a method of qualitatively testing the free fatty acid concentration of shortening.

Fats or shortening used for frying foods are composed generally of glycerine and fatty acids. Prolonged use of the shortening causes a progressive buildup of an undesirable constituent known as free fatty acids. The formation of the free fatty acids has been attributed to the breakdown of the chemical bond between the glycerine and fatty acids which make up the shortening. This breakdown is due mainly to hydrolysis, the presence of contaminating impurities in the shortening, and sustained use of the shortening at high temperatures. As the concentration of the free fatty acids increases, the shortening takes on the undesirable characteristics of foaming, dark amber color, off-flavor, smoking, and formation of gums and residues. Finally, the shortening completely breaks down and can no longer be used. Most often the user will add new shortening as the level of shortening in the cooking vessel diminishes and thereby reduces the concentration of the free fatty acids. By regularly adding new shortening to used shortening, complete breakdown can be avoided. However, the procedure of adding new shortening when the level of used shortening is low is undesirable since the used shortening may have already broken down and the new shortening, in any amount, will not render the mixture edible. There is a standard test procedure for determining the free fatty acid concentration in shortening; but, this procedure is cumbersome and not as a general rule used by restaurant operators. In other words, few users will test used shortening for free fatty acid concentration before adding new shortening.

The standard test procedure followed in determining the free fatty acid concentration of shortening, as stated above, is cumbersome, and, indeed, impractical for the busy restaurant operator. The first step of the standard procedure is to thoroughly mix a sample of test shortening and either heat or cool it to about 200 F. The sample is then carefully measured to 32.5 ml. and placed in aflask. Then, about drops of a 1.0 percent phenolphthalein solution is thoroughly mixed with a neutralized solution of isopropyl alcohol, and 0.100 N sodium hydroxide is titrated into the alcohol solution until a faint pink color appears which persists for at least 30 seconds. Then 50 ml. of the alcohol solution is thoroughly mixed with the 32.5 ml. of the test shortening and at least a full medicine dropper of phenolphthalein added to the mixture. An automatic buret is filled to its zero mark with 0.100 N sodium hydroxide solution, and slowly titrated into the flask containing the shortening-alcohol sample while continuously swirling the flask. The titration is continued until a definite pink color appears in the shortening-alcohol sample. At this point the buret is read to the nearest 0.1 ml. to determine the amount of sodium hydroxide solution used in the titration. Each whole number (i.e. 1.0 ml.) is equal to 0.1 percent free fatty acid in the shortening sample. For example 5.2 ml. equals 0.52 percent free fatty acids.

The above test would be repeated on a regular basis, and, needless to say, is very time consuming. The restaurant operator cannot afford the time necessary to run the shortening test outlined above. Furthermore, he does not need to know the exact concentration of free fatty acids in the shortening, but only needs to know whether the free fatty acid concentration is at or above the point where the shortening is no longer edible by government standards. It is an accepted fact among shortening users that shortening having a concentration of free fatty acids of 1.5 percent or more is inedible and should be discarded. Thus, all the restaurant operator wants to know is whether the shortening he is using is edible, i.e. has less than 1.5 percent free fatty acids. If his shortening is edible, he can then add new shortening to decrease the free fatty acid concentration; if not, he would discard the used shortening.

l overcome the problems inherent in the guessing as to when new shortening should be added to used shortening, ad the cumbersome and time-consuming test procedure for accurately determining the free fatty acid concentration of used shortening as a prerequisite for adding new shortening, by providing a simple and quick method for qualitatively determining the edibility of used shortening. All that my invention requires the user to do is to add a measured volume of shortening to a container having a fixed amount of test solution in it, shake the container, and observe the color of the mixture. More specifically, I provide a method of testing shortening to qualitatively determine the concentration of free fatty acids therein, which, in preferred practice, comprises the steps of: admixing a measured volume of liquid shortening having an unknown concentration of free fatty acids in a container of a known volume of an alcohol-sodium hydroxide test solution having a fixed alkaline concentration equivalent to a known concentration of free fatty acids, the test solution also including an alkaline indicator which will change color if the amount of free fatty acid in the shortening is substantially equivalent to or greater than the alkaline concentration of the test solution; agitating the container to thoroughly mix the shortening and test solution; and observing the mixture immediately after agitating to ascertain any change in color of the test solution resulting from the test solution becoming either neutral or acidic. I use the expression "qualitatively" herein for sake of ease of description and not in the strict chemical analysis sense. The method of testing of this invention shows whether shortening has a free fatty acid concentration more than, less than or the same as a known concentration. Therefore, qualitativeis used herein in the sense of showing the free fatty acid concentration of a sample of shortening relative to a known value (i.e. more than, less than or the same as the known value).

Other details and advantages of the invention will become apparent as the following description of a present preferred method of practicing the same proceeds.

In the single accompanying drawing 1 show, in perspective, a small container of test solution for use with the method of the present invention.

The single drawing shows a container 10 having an open top closed by a screwed-on cap 12. The container is formed from any well-known translucent or transparent material, and should be preferably small in size, e.g. ml. The container 10 has a known volume of test solution 14 therein and this volume fills the space in the container from the bottom thereof to the first scribe mark 16 located intermediate the ends of the container. A second scribe mark 18 is located on the container above the first scribe mark, and denotes the amount of test shortening to be put into container 10. The amount of test shortening will be equal to the volume of container 10 extending between the two scribe marks. The relative volumes of test solution to test shortening will be elaborated hereinafter.

Test solution is prepared and placed in container 10 up to the first scribe mark 16. The container is capped and stored until ready to be used. When it is desired to test a sample of shortening, the cap 12 is removed, liquid shortening is poured into container until the second scribe mark 18 is reached. The container 10 is then shaken to thoroughly mix the test solution and shortening. The color of the mixture is immediately observed.

Basically, the test solution is a solution of t-butyl alcohol and aqueous sodium hydroxide, with an alkali indicator added to show an alkaline state of the solution. More precisely, the test solution is prepared in the following manner. Water and tbutyl alcohol are mixed and neutralized. An aqueous solution of 0.100 N sodium hydroxide is mixed with the neutralized tbutyl alcohol to give the resulting solution an alkaline concentration equivalent to a fixed concentration of free fatty acid in shortening desired to be tested. For example, if it is desired to qualitatively check a sample of shortening to determine whether it has 0.5 percent or more of free fatty acid an equivalent amount of 0.100 N aqueous sodium hydroxide is added to a known volume of the aqueous t-butyl alcohol solution. More specifically, if a free fatty acid concentration of 1.5 percent is the desired test point for determination the following proportions of the constituents of the test solution will be combined: 5400 ml. of t-butyl alcohol, 2,160 ml. of water, and 250.92 ml. of 0.100 N aqueous sodium hydroxide. The constituents should be thoroughly mixed. Alkali indicator solution is added to the test solution to give it color and in the above example 8.23 ml. of 1.0 percent phenolphthalein solution should be added to give the test solution a purplish color. .T he indicator solution should be added when the water and alcohol are being mixed together. After the above batch of test solution, plus indicator, is prepared, it should immediately be placed in containers, sealed, and stored in a dark and preferably airtight place.

The amount of test solution taken from batches made with the proportions set out above, and put into container would be approximately 75.7 ml. To this amount of test solution will be added approximately 5.3 m1. of test shortening. Thus, the first scribe mark 16 will be a measure of approximately 75.7 ml. and between the first scribe mark 16 and second scribe mark 18 will be a measure of approximately 5.3 ml. It should be readily apparent that the proportions of the constituents of the test solution can be varied for any desired free fatty acid equivalency point. Also, other alcohols, such as isopropyl alcohol can be used in the test solution.

The test sample of shortening should be liquid and at a temperature of no greater than 200 F. The shortening would be added to the container of test solution and the container capped and then shaken. If the color of mixture remains purplish, or is pink or coral, then the free fatty acid concentration in the test shortening is less than 1.5 percent. Accordingly, the shortening is still edible. On the other hand, if the color of the mixture promptly changes to white, tan, light brown, brown, or becomes essentially colorless, then the shortening contains 1.5 or more percent of free fatty acid, is inedible, and should be discarded.

It should now be better appreciated that the method of testing shortening of this invention is very simple and can be conducted in a very short period of time. It is again noted, and it should now be apparent to those skilled in this art, that there are many possible variations in the proportions of the constituents of the test solution, as well as in the proportions of volumes of test solution to test shortening, for satisfying any desired free fatty acid concentration determination. In other words, this invention is not limited to a method for determining whether shortening has 1.5 or more percent free fatty acid. Rather the method contemplates determination of any practical percentage of free fatty acid, and this can be achieved by simply varying the proportions of the constituents of the test solution or the proportion of test solution to test shortening.

While 1 have illustrated a preferred method of practicing my invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously practiced within the scope of the following claims.

I claim:

1. A solution for qualitatively determining the concentration of free fatty acids in liquid shortening comprising: l-butyl alcohol, aqueous sodium hydroxide and an alkaline indicator, said solution having a fixed alkaline concentration equivalent to a known concentration of free fatty acid and being carried in a sealed container. 

